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// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package git
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"hash"
"strconv"
"strings"
)
type ObjectID interface {
String() string
IsZero() bool
RawValue() []byte
Type() ObjectFormat
}
type Sha1Hash [20]byte
func (h *Sha1Hash) String() string {
return hex.EncodeToString(h[:])
}
func (h *Sha1Hash) IsZero() bool {
empty := Sha1Hash{}
return bytes.Equal(empty[:], h[:])
}
func (h *Sha1Hash) RawValue() []byte { return h[:] }
func (*Sha1Hash) Type() ObjectFormat { return &Sha1ObjectFormat{} }
func NewSha1() *Sha1Hash {
return &Sha1Hash{}
}
// NewHash is for generic implementations
func NewHash(hash string) (ObjectID, error) {
hash = strings.ToLower(hash)
switch hash {
case "sha1":
return &Sha1Hash{}, nil
}
return nil, errors.New("unsupported hash type")
}
func IDFromRaw(h ObjectFormat, b []byte) (ObjectID, error) {
if len(b) != h.FullLength()/2 {
return h.Empty(), fmt.Errorf("length must be %d: %v", h.FullLength(), b)
}
return h.MustID(b), nil
}
func MustIDFromString(h ObjectFormat, s string) ObjectID {
b, _ := hex.DecodeString(s)
return h.MustID(b)
}
func genericIDFromString(h ObjectFormat, s string) (ObjectID, error) {
s = strings.TrimSpace(s)
if len(s) != h.FullLength() {
return h.Empty(), fmt.Errorf("length must be %d: %s", h.FullLength(), s)
}
b, err := hex.DecodeString(s)
if err != nil {
return h.Empty(), err
}
return h.NewID(b)
}
func IDFromString(hexHash string) (ObjectID, error) {
switch len(hexHash) {
case 40:
hashType := Sha1ObjectFormat{}
h, err := hashType.NewIDFromString(hexHash)
if err != nil {
return nil, err
}
return h, nil
}
return nil, fmt.Errorf("invalid hash hex string: '%s' len: %d", hexHash, len(hexHash))
}
func IsEmptyCommitID(commitID string) bool {
if commitID == "" {
return true
}
id, err := IDFromString(commitID)
if err != nil {
return false
}
return id.IsZero()
}
// HasherInterface is a struct that will generate a Hash
type HasherInterface interface {
hash.Hash
HashSum() ObjectID
}
type Sha1Hasher struct {
hash.Hash
}
// ComputeBlobHash compute the hash for a given blob content
func ComputeBlobHash(hashType ObjectFormat, content []byte) ObjectID {
return ComputeHash(hashType, ObjectBlob, content)
}
// ComputeHash compute the hash for a given ObjectType and content
func ComputeHash(hashType ObjectFormat, t ObjectType, content []byte) ObjectID {
h := hashType.NewHasher()
_, _ = h.Write(t.Bytes())
_, _ = h.Write([]byte(" "))
_, _ = h.Write([]byte(strconv.FormatInt(int64(len(content)), 10)))
_, _ = h.Write([]byte{0})
return h.HashSum()
}
// HashSum generates a SHA1 for the provided hash
func (h *Sha1Hasher) HashSum() ObjectID {
var sha1 Sha1Hash
copy(sha1[:], h.Hash.Sum(nil))
return &sha1
}
type ErrInvalidSHA struct {
SHA string
}
func (err ErrInvalidSHA) Error() string {
return fmt.Sprintf("invalid sha: %s", err.SHA)
}
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